Your 8.7 i530 engine is not something I'm familiar with. CAT? Detroit?
We have a Cummins 8.9 ISL in our 2004 Allure. Our coach came with one Chassis 8D, and two House 8D's. When I went to replace mine, a member on the Yahoo CC User Group pointed me at the CAT 8D Maintenance Free battery. He said it was the highest CCA 8D he could find, at 1500. I looked some too, and came to the same conclusion. Oddly, the CAT battery is allowed to turnover my Cummins
! I really like the MF aspect, so far in 8 months - zero outgassing, not so with the old wet cell Deka it replaced.
On House. Only you can decide your needs for size of bank Amp Hours. If you don't boondock much, or ever - then sure, the T105's will cover you.
I went the other way, and in the same foot print of our two old house 8D's, I placed X's 4 Lifeline AGM L16's, for 800AH house bank. (We do a mix of boondocking and plugged in parking.
If you don't mind wet batteries, and you mentioned T105's so I figure you don't. (We have electronic components in this battery compartment too, so I wanted to reduce the outgassing as much as possible. Along with the faster recharging times of AGM's.)
Another option, is to go with T145's, if you have enough head room. More power the T105's, same foot print. And yeah, more money too...
If you do not see a need for a high bank hour capacity, many are very happy with the Costco/Sams/Wallmart Golf Cart batteries too.
Lots of options, and it comes down to the the size of bank hours you want, and the amount of funds you want to spend.
I would anticipate that you would be OK with one Chassis 8D, but again, not real familiar with that engine nomenclature. (Though old memory cells makes me think of International engines NAV's?).
One tip, adding our year and engine might help with more finite responses - instead of speculation as I have provided?
Best of luck, and enjoy your coach,